Bird flu is caused by a type of influenza virus that rarely infects humans. But when bird flu does strike humans, it's often deadly. More than half the people who become infected with bird flu die of the disease.

What is it?

  • Bird flu is caused by a type of influenza virus that rarely infects humans. But when bird flu does strike humans, it's often deadly. More than half the people who become infected with bird flu die of the disease.
  • In recent years, outbreaks of bird flu have occurred in Asia, Africa and parts of Europe. Most people who have developed symptoms of bird flu have had close contact with sick birds. In a few cases, bird flu has passed from one person to another.
  • Health officials worry that a global outbreak could occur if a bird flu virus mutates into a form that transmits more easily from person to person. Researchers are working on vaccines to help protect people from bird flu.


Signs and symptoms of bird flu typically begin within two to five days of infection. In most cases, they resemble those of conventional influenza, including:

  • Cough
  • Fever
  • Sore throat
  • Muscle aches
  • Some people also experience nausea, vomiting or diarrhea. And in a few cases, a mild eye infection (conjunctivitis) is the only indication of the disease.


  • Bird flu occurs naturally in wild waterfowl and can spread into domestic poultry, such as chickens, turkeys, ducks and geese. The disease is transmitted via contact with an infected bird's feces, or secretions from its nose, mouth or eyes.
  • Open-air markets, where eggs and birds are sold in crowded and unsanitary conditions, are hotbeds of infection and can spread the disease into the wider community.
  • According to the Food and Drug Administration, bird flu cannot be transmitted by eating properly cooked poultry meat or eggs from infected birds. Poultry meat is safe to eat if it's been cooked to an internal temperature of 165 F (74 C). Eggs should be cooked until the yolk and white are firm.

Risk factors

The greatest risk factor for bird flu seems to be contact with sick birds or with surfaces contaminated by their feathers, saliva or droppings. The World Health Organization (WHO) has confirmed a handful of cases of limited human-to-human transmission of bird flu. But unless the virus begins to spread more easily among people, infected birds or associated material presents the greatest hazard.

The pattern of human transmission remains mysterious. Young children seem especially vulnerable to the virus, although some experts note that children are more likely to have contact with sick birds or to play on ground contaminated with droppings. What's more, people of all ages have contracted and died of bird flu. At this point, too few people have been infected to know all the possible risk factors for bird flu.


People with bird flu may develop life-threatening complications, including:

Although bird flu kills more than half the people it infects, the number of fatalities is still low because so few people have had bird flu. According to the World Health Organization, a few hundred people have died of bird flu since 2003.


Laboratory tests 

Samples of fluids from your nose or throat can be tested for the presence of a flu virus. In the past, these types of tests could take hours or even weeks to complete. When more-rapid tests became available, they couldn't distinguish between bird flu and other types of influenza. The Food and Drug Administration recently approved a type of test that can identify bird flu viruses in less than an hour.

Imaging tests 

X-rays may be useful in assessing the condition of your lungs, which can help determine the proper diagnosis and the best treatment options for your signs and symptoms.

Treatments and drugs


Many influenza viruses have become resistant to the effects of a category of antiviral drugs that includes amantadine and rimantadine. Health officials recommend the use of oseltamivir (Tamiflu) and possibly zanamivir (Relenza) instead.

These drugs must be taken within two days after the appearance of symptoms, something that may prove logistically difficult on a worldwide scale, even if there were enough to go around. Because they're in short supply, it's not entirely clear how flu drugs would be allocated if there were a widespread epidemic.


Bird flu vaccine 

The Food and Drug Administration has approved one vaccine to prevent infection with one strain of H5N1 bird flu virus. This vaccine isn't available to the public, but the U.S. government is stockpiling it and will distribute it in the event of an outbreak. It's intended to help protect adults ages 18 to 64 and could be used early in such an outbreak to provide limited protection until another vaccine — designed to protect against the specific form of the virus causing the outbreak — is developed and produced.

Researchers continue to work on other types of bird flu vaccines. One of the stumbling blocks is that most vaccines need chicken eggs for their development and production. Bird flu viruses are lethal to chicken eggs.

Recommendations for travelers

 If you're traveling to Southeast Asia or to any region with bird flu outbreaks, consider these public health recommendations:

  • Avoid domesticated birds. If possible, avoid rural areas, small farms and open-air markets.
  • Wash your hands. This is one of the simplest and best ways to prevent infections of all kinds. When you're traveling, alcohol-based hand sanitizers containing at least 60 percent alcohol are an excellent choice. They are effective, easy to use, don't require water and they're safe for children.
  • Ask about a flu shot. Before traveling, ask your doctor about a flu shot. It won't protect you specifically from bird flu, but it may help reduce the risk of simultaneous infection with bird and human flu viruses.

Poultry and egg products 

Because heat destroys avian viruses, WHO officials don't consider cooked poultry a health threat. Even so, it's best to take precautions when handling and preparing poultry, which is often contaminated with salmonella or other harmful bacteria.

  • Avoid cross-contamination. Carefully wash cutting boards, utensils and all surfaces that have come into contact with raw poultry in hot, soapy water.
  • Cook thoroughly. Cook chicken until the juices run clear, and it reaches a minimum internal temperature of 165 F (74 C).
  • Steer clear of raw eggs. Because eggshells are often contaminated with bird droppings, avoid mayonnaise, hollandaise sauce, ice cream, and any other foods containing raw or undercooked eggs.